Cylindrical grinding worms are used for the continuous generation grinding of gear wheels. Because the grinding worm is subject to natural wear and tear during this process, it must be trued from time to time. In the truing process, material is machined off the flanks or the treads of the grinding worm so that the head area of the thread(s) is getting narrower. Therefore, in addition to the tool for the profiling of the grinding worm, a tool is also required to adapt the diameter of the addendum circle of the grinding worm. The diameter of the addendum circle is decreased such that the head area of the thread(s) of the grinding worm again has the originally provided width.
Thus, the means for truing the grinding worm therefore comprises two separate tools. The tool for the profiling of the flanks of the grinding worm, for example, can be a profile-grinding wheel. With two such tools, the truing of the grinding worm is generally not effected at the place on the machine where the workpiece, i.e. the gear wheel, will be machined later on. However, for reasons of precision, it is desired that the truing process occur at the location where the grinding worm later machines the workpieces.
It has been proposed in U.S. Patent Application Publication No. 2004/0005843 (corresponding to German Patent Application Publication No. 102 20 513) to use an essentially cylindrical gear wheel to profile the flanks of the grinding worm. The profiling gear has an abrasive coating on the surface that is active during truing and the gear is taken up on the work piece spindle of the machine in place of the work piece. Because the only function of said gear is to profile the flanks of the grinding worm, an additional means to adapt the diameter of the addendum circle of the grinding worm is required.
The invention is based on the problem to develop the generic truing tool such so as to simplify the loading concept and shorten the duration of the machining of the grinding worm.